1. Field of the Invention
The present invention relates to a flame retardant ethylene family resin composite suitable for coverage of electric wires or cables, and a flame retardant electric wire or cable using the composite.
2. Description of the Related Art
Electric wires or cables, requiring the prevention of the emission of smoke as well as detrimental halogen gases due to the spread of fire, have materials covering their conductors composed, typically, by evenly mixing, in (an) ethylene family base polymer(s), a flame retardant agent containing a halogen-free metal hydrate. In cases requiring a high flame retardancy, e.g. to JIS (Japanese Industrial Standard) C3005 (60-degree inclination burning test), an assisting flame retardant agent suitable to the flame retardant agent is added.
Flame retardant agents containing magnesium hydroxide exhibit good flame retardancy. As an assisting flame retardant agent suitable to those agents, polyorganosilane is known. However, this is liquid, and thus unable to be so evenly dispersed as those, thus causing seam cracks.
Japanese Patent Application Laying-Open Publication No. 8-113712 has disclosed a method of mixing polyorganosilane and silica powder to obtain silicone polymer powder that can flow with ease, and employing this as an assisting flame retardant agent.
This method is depicted in FIG. 9, where a flame retardant agent R10 composed by magnesium hydroxide 100 covered with stearic acid or ammonium molybdate 101 and an assisting flame retardant agent R11 composed by silicon oxide 110 covered with polyorganosilane 111 are blended in a base polymer.
Polyorganosilane 111 can thus be relatively easily dispersed. It however is not easy to disperse this as uniformly as the flame retardant agent R10.